Differential expression of alkaline and neutral invertases in response to environmental stresses: characterization of an alkaline isoform as a stress-response enzyme in wheat leaves.

VARGAS WA, PONTIS HG, SALERNO GL

PLANTA

SPRINGER

Año: 2007 vol. 226 p. 1535 - 1545

0032-0935

It is well accepted that sucrose (Suc) metabolism is involved in responses to environmental stresses in many plant species. In the present study we showed that alkaline invertase (A-Inv) expression is up-regulated in wheat leaves after an osmotic stress or a low-temperature treatment. We demonstrated that the increase of total alkaline/neutral Inv activity in wheat leaves after a stress could be due to the induction of an A-Inv isoform. Also, we identified and functionally characterized the first wheat cDNA sequence that codes for an A-Inv. The wheat leaf fulllength sequence encoded a protein 70% similar to a neutral Inv of Lolium temulentum; however, after functional characterization, it resulted to encode a protein that hydrolyzed Suc to hexoses with an optimum pH of 8, and, consequently, the encoding sequence was named Ta-A-Inv. By RT-PCR assays we demonstrated that Ta-A-Inv expression is induced in response to osmotic and cold stress in mature primary wheat leaves. We propose that Ta-A-Inv activity could play an important role associated with a more eficient cytosolic Suc hydrolysis during environmental stresses.